The present invention relates to an electrostatic micro-motor apparatus capable of transmitting the driving force of an electrostatic micro-motor acting as a driving source of a micro-machine, which is produced by methods of producing semiconductors, e.g. etching, lithography, etc.
An electrostatic micro-motor apparatus is described in, for example, a paper entitled "IC-Processed Micro-Motors: Design, Technology, and Testing" (Proceedings of IEEE Micro Electro Mechanical Systems Workshop, Feb. 1989) by Tai et al. This known electrostatic micro-motor apparatus is shown in FIGS. 1 and 2 and is produced by methods of producing semiconductors, for example, etching, lithography, etc. As shown in FIG. 1, the known electrostatic micro-motor apparatus includes a support shaft 1, a rotor 2 formed with four cruciform projections having a maximum diameter of 120 .mu.m and 12 electrodes 3a-3l provided radially relative to a rotational axis of the rotor 2. Although not specifically shown, the electrodes 3a-3l are divided into three sets each having four of the electrodes 3a-3l and the three sets are connected in parallel such that a three-phase four-pole motor is obtained. More concretely, the first set includes the electrodes 3a, 3d, 3g and 3j and the second set includes the electrodes 3b, 3e, 3h and 3k, while the third set includes the electrodes 3c, 3f, 3i and 3l.
As shown in FIG. 2, the support shaft 1 is placed on a reference layer 4. The rotor 2 is supported between an upper flange 1a and a lower flange 1b so as to be prevented from coming into contact with the reference layer 4. The electrodes 3a-3l are so provided as to have a height substantially equal to that of the rotor 2. The rotor 2 has an inner peripheral contact portion 2a held in contact with the support shaft 1 and an outer peripheral portion 2b. The electrodes 3a-3l have inner peripheral portions 3a'-3l', respectively as shown in FIG. 1. The support shaft 1, the rotor 2, the electrodes 3a-3l and the reference layer 4 are made of polycrystalline silicon. A film of silicon nitride (Si.sub.3 N.sub.4) acting as a lubricating layer is coated on the inner peripheral portion 2a and the outer peripheral portion 2b of the rotor 2 and the inner peripheral portions 3a'- 3l' of the electrodes 3a-3l.
In the known electrostatic micro-motor apparatus of the above described arrangement, a voltage of about 60 to 400 V is sequentially applied to the three-phase four-pole electrodes 3a-3l through changeover of the phases. Thus, an electrostatic attractive force is exerted between end portions of the rotor 2 and the electrodes 3a-3l so as to rotate the rotor 2. For example, when the voltage is sequentially applied to the first set of the electrodes 3a, 3d, 3g and 3j, the second set of the electrodes 3b, 3e, 3h and 3k and the third set of the electrodes 3c, 3f, 3i and 3l, the rotor 2 is rotated in the direction of the arrow X in FIG. 1.
However, in the known electrostatic micro-motor apparatus, it is possible to rotate the rotor 2 but it is impossible to take out its rotational driving force. Thus, since the known electrostatic micro-motor apparatus has such a construction as an electric motor for general purpose, in which a gear is mounted on a shaft afterwards, it is impossible to effectively apply semiconductor production methods to the known electrostatic micro-motor apparatus in order to mass produce compact and light electrostatic micro-motor apparatuses having high reliability. Therefore, the known electrostatic micro-motor apparatus has such a drawback that it is impossible to formulate a micro-machine employing the known electrostatic micro-motor as its driving source.